Bump postcss from 8.4.39 to 8.4.45 in /ui

Bumps [postcss](https://github.com/postcss/postcss) from 8.4.39 to 8.4.45.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.4.39...8.4.45)

---
updated-dependencies:
- dependency-name: postcss
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

ui/package.json

@@ -37,7 +37,7 @@
     "normalize.css": "^8.0.1",
     "nprogress": "^0.2.0",
     "parse-content-range-header": "^0.2.4",
-    "postcss": "^8.4.39",
+    "postcss": "^8.4.45",
     "react": "^18.3.1",
     "react-dom": "^18.3.1",
     "react-modal": "^3.16.1",